[Cialug] ubuntu disk storage

[chris at bynw.com]

Is there a good tutorial on mdadm

On 2022-02-22 11:58, Dave Hala wrote:
> It depends on what type of hardware you have.  If you have a hardware 
> raid
> controller, backup home, then create a monster hardware raid 6 or 10
> partition with all drives, then create a new LVM partition on top of it 
> and
> then add it to the home drive.
> 
> If you don't have a hardware raid controller, then create a software 
> raid
> partition using mdadm, and then do the same as above.
> 
> Personally, both software raid (mdadm) and hardware raid work well, but
> mdadm (software raid) on linux requires command line administration and 
> is
> more of pain a when you ned to replace drives, etc.  Not that it can't 
> be
> done easily, but replacing a drive isn't something you do often, so 
> it's
> likely you'll need to dig around in your setup and config documentation
> whenever you need to do anything and that can be a pain.
> 
> :) Dave
> 
> On Tue, Feb 22, 2022 at 11:50 AM Scott Yates <Scott at yatesframe.com> 
> wrote:
> 
>> Your best bet is to pull a full backup of /home and start over I would
>> think.
>> LVM does not do redundancy.  For that you need mdadm i think, and
>> preferably, zfs for it's block level corruption self healing.
>> 
>> 
>> On Tue, Feb 22, 2022 at 11:46 AM <chris at bynw.com> wrote:
>> 
>> > I did explain that if we moved the /home directory to the LVM space
>> > there could be a loss if one of the physical drives in the LVM space
>> > died. It wasn't a concern. So I followed the instructions here:
>> > https://techsparx.com/linux/disks/ubuntu-move-home.html to move /home to
>> > the "2nd drive" aka the LVM space.
>> >
>> > But since the weekend has passed he's changed his mind. And wants the
>> > LVM space to be a RAID so the /home directory doesn't die without some
>> > form of redundancy.
>> >
>> > I'm not sure I can move the /home back to the main drive or change the
>> > LVM space to a RAID without totally redoing things on the LVM but that
>> > would also mean I have to move the /home directory back to the primary
>> > drive. And I cant figure out how to get that done.
>> >
>> > -Chris
>> >
>> > On 2022-02-18 15:11, L. V. Lammert wrote:
>> > > On Fri, 18 Feb 2022 chris at bynw.com wrote:
>> > >
>> > >> Actually Dave's response and the others have been very helpful on this
>> > >> little learning project. Thank you so much.
>> > >> Next question ..... can I move the /home directory to this LVM space??
>> > >>
>> > > Sure, ... but remember, there is no redundance with LVM - a LVM is
>> > > "logical", and relies on the underlying "physical" layer to provide
>> > > reduncancy a la RAID.
>> > >
>> > > All LVM provides is the ability to span multiple physical partitions
>> > > into
>> > > a single logical partition, .. if one drive dies, everything is toast
>> > > unless the physical volumes are part of a RAID configuration.
>> > >
>> > > That is the main reason I prefer RAID6 over LVM - much easier to
>> > > extend,
>> > > and much simpler to manage with mdadm.
>> > >
>> > >       Lee
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